Sensor for lead(II) ion based on a glassy carbon electrode modified with double-stranded DNA and ferric oxide nanoparticles

Shuttle-like Fe(2)O(3) nanoparticles (NPs) were prepared by microwave-assisted synthesis and characterized by scanning electron microscopy and X-ray diffraction. The NPs were immobilized on a glassy carbon electrode and then covered with dsDNA. The resulting electrode gives a pair of well-defined redox peaks for Pb(II) at pH 6.0, with anodic and cathodic peak potentials occurring at -0.50 V and -0.75 V (vs. Ag/AgCl), respectively. The amperometric response to Pb(II) is linear in the range from 0.12 to 40 nM, and the detection limit is 0.1 nM at a signal-to-noise ratio of 3. The sensor exhibits high selectivity and reproducibility.